Related: Remember, bugs have exoskeletons. This means if you hit them with a water-absorbing liquid, they explode from the outside in. I do this frequently with my favorite water-absorbing chemical, engine degreaser. Even the gay california low VOC brake cleaner will kill a roach in under 5 seconds, it will litterally explode it's organs out in a huge mess. The good full chlorinated russian/chinese stuff is probably still legal in egypt and will make them explode bigger, better, faster. WD40 works too but takes about a minute.

Example of what I'm talking about. This is the full strength hardcore stuff that is banned in America for killing small children:

partsource.ca/products/certified-chlorinated-brake-cleaner-525-g